Switchgear operating mechanism

Abstract

An electromagnetic rebound mechanism unit and a magnetic latch unit are fixedly installed between a switchgear and a spring drive unit by virtue of a rebound fixing member and a fixing yoke. The electromagnetic rebound mechanism unit includes a rebound coil fixedly secured to the rebound fixing member, a reinforcing plate fixedly secured to a movable shaft and a rebound ring fixedly secured to the reinforcing plate. The magnetic latch unit includes a permanent magnet fixedly secured to the rebound fixing member, a latch ring fixedly secured to the permanent magnet and a movable yoke fixedly secured to the movable shaft. The spring drive unit includes a support frame, a spring retaining plate, a circuit-opening spring, a damper unit, and first and second electromagnetic solenoids.

What is claimed is: 
     
       1. A switchgear operating mechanism which operates a movable shaft extending from a movable electrode of a switchgear to thereby bring the movable electrode into contact or out of contact with a fixed electrode, comprising:
 an electromagnetic rebound mechanism unit; 
 a magnetic latch unit; and 
 a spring drive unit, 
 wherein the electromagnetic rebound mechanism unit and the magnetic latch unit are fixedly installed between the switchgear and the spring drive unit by virtue of a fixing member, 
 the electromagnetic rebound mechanism unit includes a rebound coil fixedly secured to the fixing member, a reinforcing plate fixedly secured to the movable shaft and a rebound ring fixedly secured to the reinforcing plate, 
 the magnetic latch unit includes a permanent magnet fixedly secured to the fixing member, a latch ring fixedly secured to the permanent magnet and a movable yoke fixedly secured on the movable shaft, and 
 the spring drive unit includes a support frame fixedly installed on the fixing member, a spring retaining plate fixedly secured to an end portion of the movable shaft, a circuit-opening spring disposed between the spring retaining plate and the support frame so as to surround the movable shaft, a damper unit fixedly installed on the support frame and an electromagnetic solenoid fixedly installed on the support frame. 
 
     
     
       2. The switchgear operating mechanism of  claim 1 , wherein the permanent magnet and the latch ring of the magnetic latch unit are formed in an annular shape so as to have a rectangular cross section and are disposed coaxially with the movable shaft,
 the permanent magnet includes axially opposite end surfaces respectively magnetized with an N-pole and an S-pole, 
 the movable yoke is formed in a hat-shaped cross section so as to have a brim portion and a head top portion, 
 when the fixed electrode and the movable electrode make contact with each other to close the switchgear, the brim portion of the movable yoke and the latch ring come close to each other and the head top portion and the fixing member come close to each other to form a closed-circuit-side magnetic circuit so that the movable yoke and the fixing member are attracted by a magnetic force of the permanent magnet, and 
 when the movable electrode is moved away from the fixed electrode to open the switchgear, the brim portion of the movable yoke and the fixing member come close to each other and an edge portion of the head top portion and an edge portion of the latch ring come close to each other to form an open-circuit-side magnetic circuit so that the movable yoke is attracted toward the latch ring by the magnetic force of the permanent magnet. 
 
     
     
       3. The switchgear operating mechanism of  claim 1 , wherein the damper unit of the spring drive unit includes a cylinder having an internal space filled with a fluid and a piston slidably disposed in the cylinder,
 a seal plate for hermetically sealing the fluid and restricting a movable extent of the piston is fixedly secured to one end portion of the cylinder, 
 an orifice hole is formed in the piston, 
 a return spring which biases the piston toward the seal plate is disposed between the piston and the cylinder within the cylinder, 
 a piston head is fixedly secured to an end portion of the piston protruding out of the cylinder, 
 the piston head and the seal plate are configured to make contact with each other, when moved in a direction in which the return spring is compressed, so as to restrict the movable extent of the piston, and 
 when the movable electrode is moved away from the fixed electrode to enable the switchgear to perform a circuit-opening operation, the spring retaining plate and the piston head make contact with each other and the piston is pushed into inside of the cylinder by a spring force of the circuit-opening spring and an inertial force of a unit including the movable shaft such that a brake force is generated to stop movement of the movable electrode and the movable shaft. 
 
     
     
       4. The switchgear operating mechanism of  claim 1 , wherein the electromagnetic solenoid of the spring drive unit includes a plurality of electromagnetic solenoids disposed around the damper unit, and
 when electric power is supplied together with a circuit-closing command during a circuit-closing operation of the switchgear, an end portion of a plunger of the electromagnetic solenoid makes contact with the spring retaining plate and moves the movable electrode toward the fixed electrode until the magnetic latch unit reaches a circuit-closing position. 
 
     
     
       5. The switchgear operating mechanism of  claim 1 , wherein a plurality of electromagnetic solenoids differing in magnetic attraction force characteristics is disposed around the damper unit. 
     
     
       6. The switchgear operating mechanism of  claim 3 , wherein when the switchgear is in a closed circuit state, a magnetic attraction force Fmc of the magnetic latch unit and an elastic force Fkc of the circuit-opening spring are set to satisfy a relationship of Fmc>Fkc, and
 when the switchgear is in an open circuit state, a magnetic attraction force Fmo of the magnetic latch unit, an elastic force Fko of the circuit-opening spring and an elastic force Fdo of the return spring of the damper unit are set to satisfy a relationship of Fko>(Fmo+Fdo).